Method and apparatus for discontinuous transmission/reception operation for reducing power consumption in cellular system

ABSTRACT

Provided is a method and apparatus for discontinuously transmitting/receiving packets for low-power consumption of a terminal in a cellular system for packet transmission. The present research provides a method and apparatus that can perform a low-power consuming operation when a terminal is in active state in a cellular system. The method for discontinuously transmitting/receiving packet data to reduce power consumption of a terminal in a cellular system, including the steps of: a) establishing discontinuous reception/transmission (DRX/DTX) parameters including discontinuous DRX/DTX cycle information for terminals operating in a transmission suspension mode, which is a sub-state of an active state; and b) performing DRX/DTX based on the DRX/DTX parameters in the terminals operating in the transmission suspension mode.

This application is a continuation application of U.S. Ser. No.12/158,628, filed Jun. 20, 2008, now U.S. Pat. No. 8,305,945, issuedNov. 6, 2012, which claims the benefit under 35 U.S.C. Section 371, ofPCT International Application Number PCT/KR2006/005664, filed Dec. 22,2006 and Korean Application No. 10-2005-0127704 filed Dec. 22, 2005 inKorea, the contents of all of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a cellular system for packet services;and, more particularly, to a method and apparatus for discontinuouslytransmitting/receiving packets to reduce power consumption of a terminalin a cellular system for packet transmission.

BACKGROUND ART

Terminals in a Wideband Code Division Multiple Access (WCDMA)Third-Generation Partnership Project (3GPP) system are divided intothose of an active state where data can be transmitted and those of anidle state. Only terminals of the idle state perform discontinuousreception (DRX) to reduce their power consumption.

To perform the DRX, a DRX cycle is determined and used for monitoringaccording to a paging occasion in a paging channel (PCH), and the DRXcycle is determined in a network and the same DRX cycle is applied toall terminals within the coverage of a predetermined base station.

In other words, in the conventional 3GPP system, terminals in an idlemode operate in sleep mode (i.e., low-power consuming operation) toreduce power consumption by using the DRX cycle, which is a systemparameter.

Whereas the WCDMA 3GPP system aims to provide circuit and packetservices in a circuit-based system, a 3GPP Long-Term Evolution (LTE),which is under standardization process to provide diverse packetservices, is a packet-based system aiming to provide only a packetservice.

Therefore, the conventional method of applying a DRX cycle only toidle-mode terminals and reducing the power consumption of the terminalsis not appropriate to the LTE system which is devised to provide apacket service having a burst characteristic.

In short, it is required to develop a method that can reduce powerconsumption not only in idle-state terminals whose session for a packetservice is terminated, but also in terminals whose session is notterminated yet but in an active state where data can be transmitted in asection where there is no data to be transmitted based on the burstcharacteristic of packet traffic to provide a packet service having aburst characteristic and diverse qualities of service (QoS).

Also, it is required to realize a method and apparatus that can reducepower consumption of a terminal by optionally determining parameters fordiscontinuous reception/transmission operation based on the QoS of apacket service provided by a cellular system such as a WCDMA 3GPP systemto thereby minimize a processing time when a terminal switches between atransmission mode (Tx on) where the terminal transmits packet data and atransmission suspension mode (Tx off) where it does not transmit packetdata; and efficiently operating the transmission suspension mode sectionwhere the terminal does not transmit packet data.

DISCLOSURE Technical Problem

It is, therefore, an object of the present invention devised to resolvethe above problems to provide a method and apparatus that can perform alow-power consuming operation when a terminal is in active state in acellular system.

Also, it is another object of the present invention to provide adiscontinuous reception/transmission (DRX/DTX) method and apparatus thatcan improve a power saving function of a terminal and minimizeprocessing time needed for switching into a low-power consumingoperation mode to thereby reduce power consumption of the terminal in acellular system for transmitting packets by determining DRX/DTXparameters according to the quality of service (QoS) of a packet serviceprovided by the cellular system for transmitting packets.

Other objects and advantages of the present invention can be understoodby the following description, and become apparent with reference to theembodiments of the present invention. Also, it is obvious to thoseskilled in the art to which the present invention pertains that theobjects and advantages of the present invention can be realized by themeans as claimed and combinations thereof.

Technical Solution

In accordance with one aspect of the present invention, there isprovided a method for discontinuously transmitting/receiving packet datato reduce power consumption of a terminal in a cellular system,comprising the steps of: a) establishing discontinuousreception/transmission (DRX/DTX) parameters including discontinuousDRX/DTX cycle information for terminals operating in a transmissionsuspension mode, which is a sub-state of an active state; and b)performing DRX/DTX based on the DRX/DTX parameters in the terminalsoperating in the transmission suspension mode.

Also, the discontinuous reception/transmission method for reducing powerconsumption of a terminal in a cellular system transmitting packets,which is suggested in the present invention, includes the steps ofestablishing DRX/DTX parameters including DRX/DTX cycle information; andperforming a low power-consuming operation based on the DRX/DTXparameters.

Also, a base station apparatus for discontinuouslytransmitting/receiving packet data to reduce power consumption of aterminal in a cellular system for transmitting packets, includes aterminal state management unit and a DRX/DTX control unit. The terminalstate management unit manages and switches the state of the terminalaccording to whether the terminal is in an idle state or an activestate. The DRX/DTX control unit establishes DRX/DTX parameters includingDRX/DTX cycle information for terminals operating in a transmissionsuspension mode, which is a sub-state of the active state, and controlsthe DRX/DTX operation based on the DRX/DTX parameters.

Also, the DRX/DTX terminal of the present invention that has a reducedpower consumption in a cellular system for transmitting packets includesa terminal state management unit and a low power-consuming operationunit. The terminal state management unit controls mode switching betweena transmission suspension mode and a transmission mode, which aresub-states of the active state. The low power-consuming operation unitestablishes DRX/DTX parameters including DRX/DTX cycle information andcontrols a terminal to perform a low power-consuming operation based onthe DRX/DTX parameters while it is in the transmission suspension mode.

Advantageous Effects

The present invention increases the capacity of an active-state terminalthat can be accommodated by a base station by variably applyingparameters for discontinuous reception/transmission (DRX/DTX) accordingto the type and QoS of a packet service provided by a cellular systemfor transmitting packets and efficiently utilizing limited radioresources for transmitting control information. The present inventionalso improves a power-saving function of a terminal and minimizesprocessing time needed for mode switching of the DRX/DTX by consumingonly power needed for a reception module of the terminal according to aDRX/DTX cycle when there are no data to be transmitted.

In addition, the present invention can perform DRX/DTX operation notonly in an idle state but in an active state to reduce power consumptionof the terminal in a cellular system for transmitting packets.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a cellular system to which the presentinvention is applied.

FIG. 2 is a view describing operation of a terminal with a base stationbased on the state of the terminal in a cellular system in accordancewith an embodiment of the present invention.

FIG. 3 is a block view showing a base station performing discontinuousreception/transmission for low power consumption in accordance with anembodiment of the present invention.

FIG. 4 is a block view showing a terminal performing discontinuousreception/transmission for low power consumption in accordance with anembodiment of the present invention.

FIG. 5 is a view showing the form of packet data which is applied to thepresent invention.

FIG. 6 is an exemplary view showing a DRX/DTX cycle allocated inaccordance with an embodiment of the present invention.

FIG. 7 is a signaling flowchart between a base station and a terminalthat perform discontinuous operation for low power consumption inaccordance with an embodiment of the present invention.

BEST MODE FOR THE INVENTION

Other objects and aspects of the invention will become apparent from thefollowing description of the embodiments with reference to theaccompanying drawings, which is set forth hereinafter. Accordingly,those skilled in the art of the present invention can easily implementthe technological concept of the present invention. Also, when it isconsidered that detailed description on a prior art related to thepresent invention may obscure the points of the present inventionunnecessarily in the description of the present invention, thedescription will not be provided. Hereinafter, specific embodiments ofthe present invention will be described in detail with reference to theaccompanying drawings.

FIG. 1 is a diagram illustrating a cellular system to which the presentinvention is applied.

A cellular system providing a packet service defines and manages thestate of a terminal as shown in FIG. 1 to efficiently operate limitedradio resources in nodes over a base station, i.e., a node B.

When a terminal is registered on a network through a base station, thestate of the terminal is defined as an attached mode 1. When a terminalis not recognized on a cellular network and the base station, or whenthe terminal is not registered, the state of the terminal is defined asa detached mode 2.

Terminals in the attached mode 1 are divided into those of an activestate 3 and those of an idle state 4 according to whether or not apacket service is provided.

The active state 3 is a state where a terminal can be allocated withradio resources for transmitting/receiving packet data under the controlof a scheduling unit disposed in a base station.

The active state 3 is divided into a transmission mode (Tx on) 5 and atransmission suspension mode (Tx off) 6 according to whether radioresources for transmitting packet data are allocated.

A conventional terminal performs a low power-consuming operation, whichis so-called a power-saving operation, by maintaining only the leastcontrol channel with a base station only in the idle state 4 where thereis no data to be transmitted/received based on the burst property ofpacket data. The terminal may enter the idle state 4 by a schedulingunit of a base station, regardless of the state of the terminal.

FIG. 2 is a view describing operation of a terminal with a base stationbased on the state of the terminal in a cellular system in accordancewith an embodiment of the present invention.

As illustrated in FIG. 2, terminals 8, 9, 10 and 11 are disposed in aservice coverage of a base station 7 in a cellular system for a packetservice and receive a service by transmitting/receiving data to/from thebase station 7.

Terminals disposed within a service coverage of a base station performdifferent operations according to the connection state shown in FIG. 1.

Terminals 10 and 11 in the idle state, which have not set up a datachannel for transmitting/receiving data to/from a base station, monitorpaging channel information by informing reception of data for call setuptransmitted from a base station according to a predetermined DRX cycleto reduce power consumption.

Meanwhile, active-state terminals are divided into those 8 thattransmit/receive data to/from a base station and do not performdiscontinuous reception/transmission (DRX/DTX) operation to reduce powerconsumption and those that perform DRX/DTX operation for lowpower-consumption in the active state.

The terminals 9 that perform the DRX/DTX operation to reducepower-consumption in the active state monitor a message informing thereception of data transmitted from a base station according to a DRX/DTXcycle.

To make terminals perform the DRX/DTX operation for low powerconsumption in the active state, the base station 7 variably allocates aDRX/DTX cycle to terminals that do not transmit/receive data to/from thebase station for a predetermined time according to the provided serviceamong the terminals receiving a service. When downlink data aregenerated, a signaling message for informing the generation of thedownlink data is transmitted according to the DRX/DTX cycle of theterminal.

Among the active-state terminals, those that have nottransmitted/received data to/from the base station for more than apredetermined time performs DRX/DTX operation for low power consumptionaccording to the DRX/DTX cycle allocated under the control of the basestation. Terminals that perform DRX/DTX operation in the active statemonitor a signaling message that informs the reception of downlink datafor each DRX/DTX period and, when data to be transmitted through anuplink are generated, transmit a signaling message informing thegeneration of the data to thereby resume to receive the service.

FIG. 3 is a block view showing a base station performing discontinuousreception/transmission for low power consumption in accordance with anembodiment of the present invention.

Referring to FIG. 3, a base station includes a base station controller110, a layer-2 processor 120, a transmitter 130, a radio frequency (RF)module 140, and a receiver 150.

The base station controller 110 includes a terminal state managementunit 111, a DRX/DTX control unit 112, a scheduling unit 113, and anetwork access unit 114.

The terminal state management unit 111 and the DRX/DTX control unit 112are constituent elements for controlling DRX/DTX operation of anactive-state terminal for low power consumption.

The terminal state management unit 111 manages the terminal according towhether the terminal is in the idle state or the active state andcontrols state shift.

The scheduling unit 113 provides information on the terminals that havenot transmitted/received data for more than a predetermined time to theterminal state management unit 111 and the DRX/DTX control unit 112among the active-state terminals and determines whether to perform theDRX/DTX operation for low power-consumption.

The DRX/DTX control unit 112 receives information on the state of theterminals and information on where the terminals havetransmitted/received data from the scheduling unit 113 and the terminalstate management unit 111, determines whether to make the active-stateterminals perform the DRX/DTX operation for low power-consumption,variably determines DRX/DTX parameters according to the quality ofservice of the provided packet service or the capability of eachterminal, and outputs them to the layer-2 processor 120.

The layer-2 processor 120 generates a control message including theDRX/DTX parameters and outputs it to the transmitter 130.

The transmitter 130 receives the control message, codes the controlmessage in a coding unit 131, performs radio resource mapping in a radioresource mapping unit 132, performs inverse Fast Fourier Transform(IFFT) in an IFFT unit 133, and transmits the result to the terminalsthrough the RF module 140.

FIG. 4 is a block view showing a terminal performing discontinuousreception/transmission for low power consumption in accordance with anembodiment of the present invention.

Referring to FIG. 4, a terminal includes a terminal controller 210, alayer-2 processor 220, a transmitter 230, an RF module 240, and areceiver 250.

The RF module 240 receives signals from a base station to which theterminal belongs, i.e., where the terminal camps in, and outputs thesignals to the receiver 250.

A terminal performing the DRX/DTX operation for low power consumptionunder the control of the base station operates the receiver 250 at everyDRX/DTX cycle, extracts symbols by performing FFT process onto thesignals of the base station inputted from the RF module 240, performssymbol mapping onto the received signals based on base stationmodulation information included in the control information in the symbolmapping unit 252, and outputs the result to the decoding unit 54.

The decoding unit 253 decodes the symbols transmitted from the symbolmapping based on base station information included in the controlinformation and outputs extracted packet information to the layer-2processor 220.

The layer-2 processor 220 outputs information received at the DRX/DTXcycle to the terminal state management unit 211 and the low-powerconsuming operation unit 212 of the terminal controller 210.

The terminal state management unit 211 and the low-power consumingoperation unit 212 determine to perform low-power consuming operationand maintain the current state, when there is no downlink signalreception information within the inputted packet information. When thereis downlink signal reception information, the low-power consumingoperation unit 212 determines to suspend the low power consumingoperation, and the terminal state management unit 211 controls theshifting from the transmission suspension mode into a transmission mode.

With no regard to the control of the base station on the reception ofthe downlink information, when data to be transmitted in the uplink aregenerated, the terminal controller 210 controls the terminal statemanagement unit 211 and the low power consuming operation unit 212 tosuspend the low-power consuming operation, determines to initiate theuplink transmission in the scheduling unit 213 regardless of the DRX/DTXcycle, generates a control message in the layer-2 processor 220, andtransmits uplink packet information to the base station through thetransmitter 230 and the RF module 240.

FIG. 5 is a view showing the form of packet data which is applied to thepresent invention.

Referring to FIG. 5, an active-state terminal defines a transmissionmode as a state that packet calls 51 burst out due to thecharacteristics of packet data and occupies radio resources allocated bya scheduling unit to transmit the packet data. When there is no packetdata to be transmitted, such as a reading time 52, the terminal definesthe state as a transmission suspension mode where the base stationperforms low power consuming operation.

Also, when the base station and the terminal recognize terminal of allsessions on service or if needed, they can shift the terminal into anidle state.

For the state shift and mode switching, they can set up DRX/DTXparameters according to the type or QoS of a packet service, and includethe DRX/DTX parameters in system information transmitted through abroadcasting channel.

The DRX/DTX parameters include a DRX/DTX cycle initial value, a minimumDRX/DTX cycle, a DRX/DTX cycle augmentative coefficient, a durationapplying a same DRX/DTX cycle, a transmission mode residue thresholdvalue, and a transmission suspension mode residue threshold value.

The DRX/DTX cycle initial value is a DRX/DTX cycle value applied to theinitial period of the transmission suspension mode.

The minimum DRX/DTX cycle is the minimum value of a coefficient forsetting up a DRX/DTX cycle that is applied to the radio resourceallocation for transmitting control information of a terminal that thescheduling unit of a base station has switched into a transmissionsuspension mode.

The DRX/DTX cycle augmentative coefficient is a coefficient value forindicating an increased amount when the DRX/DTX cycle of terminals whichare switched into the transmission suspension mode and perform theDRX/DTX operation.

The duration applying a same DRX/DTX cycle is a value of a counter or avalue set up as time to increase a DRX/DTX cycle after maintaining ituniformly as long as a duration applying a same DRX/DTX cycle, when theDRX/DTX cycle is increased as much as the DRX/DTX cycle augmentationcoefficient during the operation of transmission suspension mode.

The transmission mode residue threshold value is a threshold value thatthe terminal can remain in the transmission mode without packet data tobe transmitted in the transmission buffers of the base station and theterminal.

The transmission suspension mode residue threshold value is a thresholdvalue that a terminal can operate in the transmission suspension modewhen the terminal does not or cannot recognize the termination of aprovided packet service.

When there are packet data in the transmission buffers of the basestation and the terminal, the terminal operates in the transmissionmode, which is a sub-state of the active state, and the scheduling unitoccupies allocated radio resources and transmits data.

The scheduling unit can switch the terminal from the transmission modeinto the transmission suspension mode in the following situations:

when packet data are not generated until the base station and theterminal set up a buffer timer at a buffer empty moment that all data tobe transmitted are transmitted and the transmission buffers of the basestation and the terminal become empty and begin counting, and the timervalue exceeds the transmission mode residue threshold value.

when it is impossible to allocate radio resources due to a poor radiocommunication environment between a node B and the terminal.

when the scheduling unit determines to switch the terminal mode into thetransmission suspension mode for other reasons.

The base station can efficiently use limited radio resources fortransmitting control information that should be allocated to theactive-state terminals by switching some terminals into the transmissionsuspension mode in the above occasions.

Also, when there is no data to be transmitted that burst out, theterminals operate in the transmission suspension mode performdiscontinuous transmission (DTX) to reduce their power consumption byusing the uplink radio resources for transmitting control information,which are allocated according to the DRX/DTX cycle and reporting theterminal buffer state and reporting the quality of an estimated downlinkchannel.

Furthermore, the process time taken for switching between thetransmission mode and the transmission suspension mode can be minimizedby properly establishing and operating the DRX/DTX cycle between thebase station and the terminal, and using an indicator for informing thepresence of downlink traffic at every DRX/DTX cycle and radio resourcesallocated to the uplink to request to switch the mode.

When the base station is switched between the transmission mode and thetransmission suspension mode, it discusses and determines DRX/DTXparameters for each terminal according to the terminal and the QoS ofthe provided packet service, and informs them to the terminal through acontrol channel. In the meantime, when there is no discussing processbetween the base station and the terminals, the terminals performsDRX/DTX operation according to the DRX/DTX parameters transmittedthrough a broadcasting channel.

The DRX/DTX cycle is determined according to the DRX/DTX parameters,which are determined between the base station and the terminals, basedon the following algorithm:

when n>0 and n mod duration applying a same DRX/DTX cycle is equal to 0,DRX/DTX cycle(n+1)=DRX/DTX cycle(n)*DRX/DTX cycle augmentationcoefficient.

In other cases,DRX/DTX cycle(n+1)=DRX/DTX cycle(n)

where n=0, 1, 2, 3 . . . , iDRX/DTX cycle(0)=DRX/DTX cycle initial value

DRX/DTX cycle augmentation coefficient=1, 2, 3 . . . , j

duration applying a same DRX/DTX cycle=time duration (or a thresholdvalue of a counter) to which the same DRX/DTX cycle is applied

FIG. 6 is an exemplary view showing a DRX/DTX cycle allocated inaccordance with an embodiment of the present invention.

When the DRX/DTX cycle initial value 63, DRX/DTX cycle augmentationcoefficient and duration applying a same DRX/DTX cycle 61 of anactive-state terminal operating in the transmission suspension mode (Txoff) are respectively 50 milliseconds, 2 and 500 milliseconds (or thecounter threshold value is determined at 10), an identical DRX/DTX cycleis applied in the DRX/DTX cycle sustaining section 61, and anotherDRX/DTX cycle which is increased by the previous DRX/DTX cycle based onthe DRX/DTX cycle augmentation coefficient is applied in the nextduration applying a same DRX/DTX cycle 61 according to the algorithm ofFIG. 6. In other words, a DRX/DTX cycle initial value of 50 millisecondsis applied in the initial duration applying a same DRX/DTX cycle, and100 milliseconds, which is twice as much as the DRX/DTX cycle initialvalue, is applied in the next duration applying a same DRX/DTX cycle.Whenever one duration applying a same DRX/DTX cycle ends ((n modduration applying a same DRX/DTX cycle)=0), the DRX/DTX cycle increasestwice as much according to the DRX/DTX cycle augmentation coefficient.

To be specific, the terminal enters into the transmission suspensionmode and performs low power-consuming operation to thereby consume theleast amount of power needed by the receiver during the DRX/DTX cycle of50 ms and suspend the operation of the transmitter and the most part ofthe receiver. At the end of the 50 ms-DRX/DTX cycle, the terminalmonitors radio resources for transmitting a traffic indicator and uplinkcontrol information. In the monitoring duration, when the terminal findsout no data to be transmitted in the uplink or no information indicatingdownlink data reception, the terminal performs the low power-consumingoperation according to the DRX/DTX cycle. In the example of parameters,the identical DRX/DTX cycle is applied during the duration applying asame DRX/DTX cycle, i.e., 500 ms, and after fall 10 monitoring durationsoccurs in one duration applying a same DRX/DTX cycle. When a counter isemployed, the counter number increases by 1 whenever one DRX/DTX cyclepasses. To sum up, in the above case, the counter number increases by 1at every 50 ms and one DRX/DTX cycle is applied until the counter numberbecomes 10.

Therefore, the terminal determines based on the algorithm whether it isin or out of a duration applying a same DRX/DTX cycle, whenever oneDRX/DTX cycle ends. When n>0, (n mod duration applying a same DRX/DTXcycle)=0. When the timer of the terminal or an independent DRX/DTX cyclecounter indicates the end of a duration applying a same DRX/DTX cycle,the terminal performs calculation to obtain a DRX/DTX cycle to beapplied in the next duration applying a same DRX/DTX cycle based on theabove algorithm equation.

When the DRX/DTX cycle augmentation coefficient is determined to be 1regardless of parameters of the duration applying a same DRX/DTX cycle,the DRX/DTX cycle of the terminal, which is in the transmissionsuspension mode, becomes the DRX/DTX cycle initial value 63 all throughthe transmission suspension mode.

The DRX/DTX parameters including the DRX/DTX cycle initial value 63 arevariably determined according to the type of a packet service and theQoS.

For example, in case of a real-time voice of IP (VoIP) service, lowpower-consuming operation can be performed based on the DRX/DTX cycleinitial value by setting up the DRX/DTX cycle initial value at 20 ms andthe DRX/DTX cycle augmentation coefficient to be ‘1’ regardless of theduration applying a same DRX/DTX cycle parameter, and limiting thevariation of the DRX/DTX cycle. To sum up, in a real-time service,overhead caused by transmitting control information can be reduced byfixing the DRX/DTX cycle and allocating radio resources periodicallybased on the DRX/DTX cycle without transmitting an additional controlmessage for the allocation of radio resources, e.g., L1/L2 controlsignaling, and the QoS of a service required by the system can beachieved while reducing the power consumption of the terminal. Herein,the DRX/DTX cycle initial value for each terminal may be set updifferently according to the type of the real-time service and thecapacity of the terminal.

Meanwhile, a short DRX/DTX cycle initial value may be determined in anon-real time http service for the Internet Access to reduce delay timeuntil data are retransmitted to the low power-consuming terminals.Generally, however, the DRX/DTX cycle initial value may be determinedrelatively larger than that of a real-time service. The throughput of asystem can be improved by determining the duration applying a sameDRX/DTX cycle to be a multiple of a Transmission Time Interval (TTI)based on the statistical characteristic of a packet service inconsideration of the load on a base station, determining the DRX/DTXcycle augmentation coefficient to be 2 or higher, and varying theDRX/DTX cycle. In short, a non-real time service is not sensitive todelay of packet data and its activity is not predicted. Therefore, it isdesirable to determine the DRX/DTX cycle initial value of a non-realtime service larger than that of a real-time service according to theload on a base station, type of non-real time service, and capacity of aterminal, and varying the DRX/DTX cycle based on the parameters of theduration applying a same DRX/DTX cycle and the parameters of the DRX/DTXcycle augmentation coefficient. The method has a shortcoming that thebase station and the terminal should exchange a control message forallocating radio resources to transmit packet data by varying theDRX/DTX cycle. However, it can efficiently reduce the power consumptionof the terminal.

A base station allocates a traffic indicator for informing that thereare packet data to be transmitted from the base station to each of theterminals operating in the transmission suspension mode, and radioresources 62 for transmitting control information in the uplink for eachDRX/DTX cycle.

When a terminal operating in the transmission suspension mode receivesan indicator informing that there are packet data to be received fromthe base station in the downlink, it transmits control information forswitching the mode through the uplink radio resources 62 allocated bythe base station and is switched into the transmission mode.

Also, the terminal operating in the transmission suspension modetransmits the control information such as the state of a terminal bufferand downlink channel quality by using the uplink radio resources 62allocated for each DRX/DTX cycle and, when there are data to betransmitted, it transmits the control information including a modeswitching request into the transmission mode by using the allocateduplink radio resources 62.

FIG. 7 is a signaling flowchart between a base station and a terminalthat perform discontinuous operation for low power consumption inaccordance with an embodiment of the present invention.

The base station determines DRX/DTX parameters based on the type and QoSof the packet service to shift the state and switch the mode of the idleterminal, generates system information including the DRX/DTX parameters,and transmits it through a broadcasting channel at step S711.

At step S712, when packet data are generated, the base station attemptsto provide a service corresponding to the packet data. Herein, the basestation attempts to provide a service through paging, and the terminalreceives system information during a paging monitoring section andattempts to access in a random access method to provide the servicecorresponding to the generated packet data.

At step S721, the terminal is shifted into the active state bycontrolling the state shift, and the terminal whose mode is shifted intothe active state operates in the transmission mode at step S722, and thebase station and terminal establishes session for the packet dataservice at step S723.

Subsequently, when the transmission buffers of the base station and theterminal remain empty in the transmission mode and there is no attemptfor a new service (buffer information timer>transmission mode residuethreshold value), the terminal switches its mode into the transmissionsuspension mode and performs DRX/DTX at steps S724 and S725. The basestation and terminal discuss and set up the DRX/DTX parameters at stepS726, and the base station transmits traffic presence indicatoraccording to the DRX/DTX cycle and allocates radio resources fortransmitting uplink control information at step S727.

Subsequently, when the terminal detects a downlink traffic indicatorduring the DRX/DTX operation in the transmission suspension mode orthere are data to be transmitted, the terminal is switched into thetransmission mode upon the state shift control (at step S728) of thebase station at step S729, and attempts to transmit the packet data orattempts to provide a new service at step S730, and cancels the sessionat step S731 when the packet data service ends. At the step S730, thebase station attempts to provide the service based on MAC paging, andwhen there is no uplink synchronization, the terminal attempts toprovide the service through random access. When the uplinksynchronization is achieved, the terminal attempts to provide theservice by using the available radio resources for transmitting thecontrol information. The MAC paging is a method that an MAC takes theinitiative and informs the terminal of the generation of data to betransmitted through downlink, instead of the Radio Resource Control(RRC). It is different from RRC-controlled paging. An example of the MACpaging is to inform transmission of scheduling information.

Meanwhile, when the terminal is in the transmission suspension mode andthe transmission suspension mode residue timer is larger than thetransmission suspension mode residue threshold value or a sessiontermination signal is generated, it shifts into the idle state at stepS732.

Also, when the terminal is in the transmission mode and the transmissionmode residue timer is larger than the transmission mode residuethreshold value or a session termination signal is generated, it shiftsinto the idle state at the step S732, too.

The method of the present invention can be realized as a program andstored in a computer-readable recording medium such as CD-ROM, RAM, ROM,floppy disks, hard disks, and magneto-optical disks. Since the processcan be easily implemented by those skilled in the art to which thepresent invention pertains, detailed description on it will not beprovided herein.

While the present invention has been described with respect to certainpreferred embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the scope of the invention as defined in the following claims.

INDUSTRIAL APPLICABILITY

The present invention is applied to a cellular system.

What is claimed is:
 1. A method for discontinuously transmitting and/orreceiving packet data to reduce power consumption of a terminal in acellular system, comprising: establishing discontinuous reception and/ortransmission (DRX/DTX) parameters including DRX/DTX cycle informationfor terminals in an active state in which the terminals are capable oftransmitting or receiving data; and performing DRX/DTX based on theDRX/DTX parameters for the terminals operating the DRX/DTX in the activestate, wherein the terminals operate in the active state or an idlestate.
 2. The method as recited in claim 1, wherein the DRX/DTXparameters further include a DRX/DTX cycle augmentation coefficient anda DRX/DTX cycle suspension section.
 3. The method as recited in any oneof claims 1 to 2, wherein the establishing further includes:transmitting the DRX/DTX parameters based on the system informationtransmitted through a broadcasting channel.
 4. The method as recited inany one of claims 1 to 2, wherein the DRX/DTX parameters are establishedbased on any one between the type and quality of service (QoS) of apacket service provided to the terminal in the establishing.
 5. Themethod as recited in claim 4, wherein when the packet service is anon-real time service, a DRX/DTX cycle is variably established in theestablishing.
 6. The method as recited in claim 4, wherein when thepacket service is a real-time service, a DRX/DTX cycle is fixed in theestablishing.
 7. The method as recited in any one of claims 1 to 2,wherein the performing DRX/DTX includes: establishing a traffic presenceindicator for informing the presence of packet traffic that the terminalis to receive and transmitting the traffic presence indicator based onthe DRX/DTX cycle to each of the terminals in the DRX/DTX operation. 8.The method as recited in any one of claims 1 to 2, wherein theperforming DRX/DTX includes: allocating uplink radio resources to theterminals in the DRX/DTX operation based on the DRX/DTX cycle, andnotifying the allocation.
 9. The method as recited in claim 8, whereinthe performing DRX/DTX further includes: receiving buffer stateinformation of each terminal through the uplink radio resourcesallocated based on the DRX/DTX cycle from the terminals in the DRX/DTXoperation.
 10. The method as recited in claim 8, wherein the performingDRX/DTX further includes: receiving the uplink radio resources allocatedbased on the DRX/DTX cycle from the terminals in the DRX/DTX operation.11. The method as recited in claim 2, wherein the performing DRX/DTXfurther includes: performing DRX/DTX by applying a DRX/DTX cycle to oneDRX/DTX sustaining section, and increasing the DRX/DTX cycle wheneverthe DRX/DTX sustaining section ends.
 12. The method as recited in claim2, wherein the establishing: whenever the duration applying a sameDRX/DTX cycle ends, establishing the DRX/DTX cycle based on thefollowing equation: DRX/DTX cycle(n+1)=DRX/DTX cycle(n)*DRX/DTX cycleaugmentation coefficient where the DRX/DTX cycle denotes the cycle ofdiscontinuous reception/transmission; the duration applying a sameDRX/DTX cycle denotes a cycle sustaining section of discontinuousreception/transmission; and the DRX/DTX cycle augmentation coefficientdenotes a cycle increasement coefficient of discontinuousreception/transmission.
 13. The method as recited in claim 2, furthercomprising: switching a terminal operating in a transmission mode intothe transmission suspension mode based on the transmission mode residuethreshold value.
 14. The method as recited in claim 2, furthercomprising: shifting the terminal operating in the transmissionsuspension mode into an idle state based on the transmission suspensionmode residue threshold value.
 15. A method for performing discontinuoustransmission and/or reception operation of a terminal in a cellularsystem, comprising: receiving discontinuous reception and/ortransmission (DRX/DTX) parameters from a base station, wherein theDRX/DTX parameters include DRX/DTX cycle information for the terminal inan active state in which the terminal is capable of transmitting orreceiving data to or from the base station; and performing, DRX/DTXoperation based on the DRX/DTX parameters in the active state, whenuplink transmission is needed in DRX/DTX operation with DRX/DTX cycle,transmitting a scheduling request to the base station, wherein theterminal operates in the active state or an idle state.